The present invention is directed to heat sinks in general, and more particularly to heat sinks for use in dissipating waste heat generated by electrical or electronic components and assemblies.
High power electrical and electronic components continue to have an increasing demand for higher power dissipation within a relatively confined space. In order to provide for such higher power dissipation requirements while remaining suitably compact, several levels of thermal management are usually required at the device, sub-assembly and component level.
At the component level, various types of heat exchangers and heat sinks have been used that apply natural or forced convection or other cooling methods. One type of prior art heat sink for electrical or electronic components is illustrated in FIG. 1 and shown generally at 10. Heat sink 10 employs a base plate 12 that has a bottom surface 16 to which the electrical device is attached and a top surface 14 to which a folded fin 18 is attached. Folded fin 18 can be formed from a continuous strip of metal in an accordion-style such that there are alternating convoluted portions 20 and planar portions 22. The folded fin 18 is placed on top surface 14 of base plate 12 such that convoluted portions 20 on one side of fin 18 are abutted to top surface 14 of the base plate 12, and then typically affixed to the base plate by brazing, soldering, or other manner of affixing to enhance the heat flow from base plate 12 to folded fin 18. An electric fan is then placed in proximity to one side of the heat sink and air is either drawn or blown through the passages 24 formed by the fins and convolutions.
There are certain inefficiencies associated with this type of design, the primary inefficiency being that the airflow does not necessarily contact all flat surfaces of the folded fin. Thus a folded fin heat sink is desired that is easy to fabricate and assemble while also provided for improved airflow and thermal conductivity away from the electrical or electronic device being cool.
One aspect of the present invention is a heat sink for cooling electrical or electronic devices. The heat sink comprises a base plate having a top surface and having a bottom surface for attaching to the electronic device. A folded fin formed from a strip of heat conducting material comprising alternating planar portions and curved portions has one edge abutted to the top surface such that the curved portions extend upwardly from the top surface substantially at a right angle. Each planar portion has a plurality of louvers formed therein wherein the louvers are substantially parallel one to the other and perpendicular to the base plate.
Another aspect of the present invention is a method of fabricating a heat sink for electrical or electronic devices. The method comprising the steps of providing a base plate having a top surface and a bottom surface. A folded fin is formed from a strip of heat conductive material wherein the folded fin has a plurality of alternating curved portions and planar portions. A plurality of louvers is formed in each of the planar portions such that the louvers are aligned substantially parallel to the curved portions. One edge of the folded fin is affixed to the base plate such that the curved portions and planar portions are substantially perpendicular to the top surface of the base plate.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.
FIG. 1 is a perspective view of a prior art heat sink, wherein the folds of the folded fin are abutted to a top surface of the base plate.
FIG. 2 is a perspective view of a heat sink embodying the present invention, wherein a louvered folded fin is mounted to a top surface of the base plate.
FIG. 3 is a plan view of the louvered fin shown in FIG. 2 illustrating the angulation of the louvers.
FIG. 4 is a partial cross-sectional view of the louver formed in the bend radius of the folded fin wherein the louver is bent away from the folded fin.
FIG. 5 is alternate embodiment of the heat sink of FIG. 4 wherein the louver in the bend radius is bent to the inside of the folded fin.
FIG. 6 is a perspective view of an alternate embodiment heat sink wherein the louvers are formed parallel with the base plate.
FIG. 7 is a perspective view of an alternate embodiment heat sink wherein the louvers are angularly oriented with respect to the base plate.